Chromosomal location of human kappa and lambda immunoglobulin light chain constant region genes

The landscape of the immunoglobulin repertoire in endemic pemphigus foliaceus

Introduction

Primarily driven by autoreactive B cells, pemphigus foliaceus (PF) is an uncommon autoimmune blistering skin disease of sporadic occurrence worldwide. However, PF reaches a prevalence of 3% in the endemic areas of Brazil, the highest ever registered for any autoimmune disease, which indicates environmental factors influencing the immune response in susceptible individuals. We aimed to provide insights into the immune repertoire of patients with PF living in the endemic region of the disease, compared to healthy individuals from the endemic region and a non-endemic area.

Methods

We characterized the B-cell repertoire in i) nontreated patients (n=5); ii) patients under immunosuppressive treatment (n=5); iii) patients in remission without treatment (n=6); and two control groups iv) from the endemic (n=6) and v) non-endemic areas in Brazil (n=4). We used total RNA extracted from peripheral blood mononuclear cells and performed a comprehensive characterization of the variable region of immunoglobulin heavy chain (IGH) in IgG and IgM using next-generation sequencing.

Results

Compared to individuals from a different area, we observed remarkably lower clonotype diversity in the B-cell immune repertoire of patients and controls from the endemic area (p < 0.02), suggesting that the immune repertoire in the endemic area is under geographically specific and intense environmental pressure. Moreover, we observed longer CDR3 sequences in patients, and we identified differential disease-specific usage of IGHV segments, including increased IGHV3-30 and decreased IGHV3-23 in patients with active disease (p < 0.04). Finally, our robust network analysis discovered clusters of CDR3 sequences uniquely observed in patients with PF.

Discussion

Our results indicate that environmental factors, in addition to disease state, impact the characteristics of the repertoire. Our findings can be applied to further investigation of the environmental factors that trigger pemphigus and expand the knowledge for identifying new targeted and more effective therapies.

Application of germline antibody features to vaccine development, antibody discovery, antibody optimization and disease diagnosis

Although the efficacy and commercial success of vaccines and therapeutic antibodies have been tremendous, designing and discovering new drug candidates remains a labor-, time- and cost-intensive endeavor with high risks. The main challenges of vaccine development are inducing a strong immune response in broad populations and providing effective prevention against a group of highly variable pathogens. Meanwhile, antibody discovery faces several great obstacles, especially the blindness in antibody screening and the unpredictability of the developability and druggability of antibody drugs. These challenges are largely due to poorly understanding of germline antibodies and the antibody responses to pathogen invasions. Thanks to the recent developments in high-throughput sequencing and structural biology, we have gained insight into the germline immunoglobulin (Ig) genes and germline antibodies and then the germline antibody features associated with antigens and disease manifestation. In this review, we firstly outline the broad associations between germline antibodies and antigens. Moreover, we comprehensively review the recent applications of antigen-specific germline antibody features, physicochemical properties-associated germline antibody features, and disease manifestation-associated germline antibody features on vaccine development, antibody discovery, antibody optimization, and disease diagnosis. Lastly, we discuss the bottlenecks and perspectives of current and potential applications of germline antibody features in the biotechnology field.

Antibodies gone bad - the molecular mechanism of light chain amyloidosis

Light chain amyloidosis (AL) is a systemic disease in which abnormally proliferating plasma cells secrete large amounts of mutated antibody light chains (LCs) that eventually form fibrils. The fibrils are deposited in various organs, most often in the heart and kidney, and impair their function. The prognosis for patients diagnosed with AL is generally poor. The disease is set apart from other amyloidoses by the huge number of patient-specific mutations in the disease-causing and fibril-forming protein. The molecular mechanisms that drive the aggregation of mutated LCs into fibrils have been enigmatic, which hindered the development of efficient diagnostics and therapies. In this review, we summarize our current knowledge on AL amyloidosis and discuss open issues.

Widespread amyloidogenicity potential of multiple myeloma patient-derived immunoglobulin light chains

BACKGROUND

In a range of human disorders such as multiple myeloma (MM), immunoglobulin light chains (IgLCs) can be produced at very high concentrations. This can lead to pathological aggregation and deposition of IgLCs in different tissues, which in turn leads to severe and potentially fatal organ damage. However, IgLCs can also be highly soluble and non-toxic. It is generally thought that the cause for this differential solubility behaviour is solely found within the IgLC amino acid sequences, and a variety of individual sequence-related biophysical properties (e.g. thermal stability, dimerisation) have been proposed in different studies as major determinants of the aggregation in vivo. Here, we investigate biophysical properties underlying IgLC amyloidogenicity.

RESULTS

We introduce a novel and systematic workflow, Thermodynamic and Aggregation Fingerprinting (ThAgg-Fip), for detailed biophysical characterisation, and apply it to nine different MM patient-derived IgLCs. Our set of pathogenic IgLCs spans the entire range of values in those parameters previously proposed to define in vivo amyloidogenicity; however, none actually forms amyloid in patients. Even more surprisingly, we were able to show that all our IgLCs are able to form amyloid fibrils readily in vitro under the influence of proteolytic cleavage by co-purified cathepsins.

CONCLUSIONS

We show that (I) in vivo aggregation behaviour is unlikely to be mechanistically linked to any single biophysical or biochemical parameter and (II) amyloidogenic potential is widespread in IgLC sequences and is not confined to those sequences that form amyloid fibrils in patients. Our findings suggest that protein sequence, environmental conditions and presence and action of proteases all determine the ability of light chains to form amyloid fibrils in patients.

Germline polymorphisms and alternative splicing of human immunoglobulin light chain genes

Inference of germline polymorphisms in immunoglobulin genes from B cell receptor repertoires is complicated by somatic hypermutations, sequencing/PCR errors, and by varying length of reference alleles. The light chain inference is particularly challenging owing to large gene duplications and absence of D genes. We analyzed the light chain cDNA sequences from naïve B cell receptor repertoires from 100 individuals. We optimized light chain allele inference by tweaking parameters of the TIgGER functions, extending the germline reference sequences, and establishing mismatch frequency patterns at polymorphic positions to filter out false-positive candidates. We identified 48 previously unreported variants of light chain variable genes. We selected 14 variants for validation and successfully validated 11 by Sanger sequencing. Clustering of light chain 5'UTR, L-PART1, and L-PART2 revealed partial intron retention in 11 kappa and 9 lambda V alleles. Our results provide insight into germline variation in human light chain immunoglobulin loci.

Immunoglobulin germline gene variation and its impact on human disease

Immunoglobulins (Ig) play an important role in the immune system both when expressed as antigen receptors on the cell surface of B cells and as antibodies secreted into extracellular fluids. The advent of high-throughput sequencing methods has enabled the investigation of human Ig repertoires at unprecedented depth. This has led to the discovery of many previously unreported germline Ig alleles. Moreover, it is becoming clear that convergent and stereotypic antibody responses are common where different individuals recognise defined antigenic epitopes with the use of the same Ig V genes. Thus, germline V gene variation is increasingly being linked to the differential capacity of generating an effective immune response, which might lead to varying disease susceptibility. Here, we review recent evidence of how germline variation in Ig genes impacts the Ig repertoire and its subsequent effects on the adaptive immune response in vaccination, infection, and autoimmunity.

De Novo Sequencing of Antibody Light Chain Proteoforms from Patients with Multiple Myeloma

In multiple myeloma diseases, monoclonal immunoglobulin light chains (LCs) are abundantly produced, with, as a consequence in some cases, the formation of deposits affecting various organs, such as the kidney, while in other cases remaining soluble up to concentrations of several g·L^-1 in plasma. The exact factors crucial for the solubility of LCs are poorly understood, but it can be hypothesized that their amino acid sequence plays an important role. Determining the precise sequences of patient-derived LCs is therefore highly desirable. We establish here a novel de novo sequencing workflow for patient-derived LCs, based on the combination of bottom-up and top-down proteomics without database search. PEAKS is used for the de novo sequencing of peptides that are further assembled into full length LC sequences using ALPS. Top-down proteomics provides the molecular masses of proteoforms and allows the exact determination of the amino acid sequence including all posttranslational modifications. This pipeline is then used for the complete de novo sequencing of LCs extracted from the urine of 10 patients with multiple myeloma. We show that for the bottom-up part, digestions with trypsin and Nepenthes digestive fluid are sufficient to produce overlapping peptides able to generate the best sequence candidates. Top-down proteomics is absolutely required to achieve 100% final sequence coverage and characterize clinical samples containing several LCs. Our work highlights an unexpected range of modifications.

Serum free light chains in solid organ transplant recipients

Immunoglobulin is built by a pair of identical heavy and a pair of identical light chains. Light chains are produced in excess compared to heavy chains. Free light chains (FLCs) are those which are not combined with heavy chains. Currently, numerous assays are available for the measurement of serum FLCs (sFLCs). These assays cannot be used interchangeably, and renal function should be taken into account in interpreting test results. Levels of kappa and lambda sFLCs are usually used to diagnose and monitor plasma cell dyscrasias. However, the clinical relevance of sFLCs is being investigated in patients with a variety of diseases, including patients after transplantation. There are contradictory results regarding the usefulness of sFLCs in the prediction of post-transplant lymphoproliferative disorder (PTLD). However, it seems that sFLCs may be helpful in the prediction of early-onset PTLD. Some studies have shown that low levels of sFLCs are associated with a higher risk of infection in patients after transplantation. This review summarizes and highlights recent advances in the utility of sFLCs in the prediction of PTLD and infection, and inflammation assessment in patients after solid organ transplantation. Moreover, the influence of immunosuppressive treatment on sFLCs levels is described briefly.

Immunoglobulins or Antibodies: IMGT® Bridging Genes, Structures and Functions

IMGT®, the international ImMunoGeneTics® information system founded in 1989 by Marie-Paule Lefranc (Université de Montpellier and CNRS), marked the advent of immunoinformatics, a new science at the interface between immunogenetics and bioinformatics. For the first time, the immunoglobulin (IG) or antibody and T cell receptor (TR) genes were officially recognized as 'genes' as well as were conventional genes. This major breakthrough has allowed the entry, in genomic databases, of the IG and TR variable (V), diversity (D) and joining (J) genes and alleles of Homo sapiens and of other jawed vertebrate species, based on the CLASSIFICATION axiom. The second major breakthrough has been the IMGT unique numbering and the IMGT Collier de Perles for the V and constant (C) domains of the IG and TR and other proteins of the IG superfamily (IgSF), based on the NUMEROTATION axiom. IMGT-ONTOLOGY axioms and concepts bridge genes, sequences, structures and functions, between biological and computational spheres in the IMGT® system (Web resources, databases and tools). They provide the IMGT Scientific chart rules to identify, to describe and to analyse the IG complex molecular data, the huge diversity of repertoires, the genetic (alleles, allotypes, CNV) polymorphisms, the IG dual function (paratope/epitope, effector properties), the antibody humanization and engineering.

Polymorphisms in human immunoglobulin heavy chain variable genes and their upstream regions

Germline variations in immunoglobulin genes influence the repertoire of B cell receptors and antibodies, and such polymorphisms may impact disease susceptibility. However, the knowledge of the genomic variation of the immunoglobulin loci is scarce. Here, we report 25 potential novel germline IGHV alleles as inferred from rearranged naïve B cell cDNA repertoires of 98 individuals. Thirteen novel alleles were selected for validation, out of which ten were successfully confirmed by targeted amplification and Sanger sequencing of non-B cell DNA. Moreover, we detected a high degree of variability upstream of the V-REGION in the 5′UTR, L-PART1 and L-PART2 sequences, and found that identical V-REGION alleles can differ in upstream sequences. Thus, we have identified a large genetic variation not only in the V-REGION but also in the upstream sequences of IGHV genes. Our findings provide a new perspective for annotating immunoglobulin repertoire sequencing data.

Free Light Chains as a Novel Diagnostic Biomarker of Immune System Abnormalities in Multiple Sclerosis and HIV Infection

Introduction

Immunoglobulins are molecules composed of two heavy and two light chains. Light chains are produced by B lymphocytes during the synthesis of immunoglobulins, and physiologically light chains are generally produced in excess compared to heavy chains. Light chains that are not combined to heavy chains in a whole immunoglobulin are called free light chains (FLCs). B-cell abnormalities are associated with disorders leading to an abnormal concentration of free light chains. In this study, we focus on the described changes of serum and cerebrospinal fluid concentration of free light chains in inflammatory disorders: multiple sclerosis, HIV infection, and HIV-associated lymphomas.

Methods

We performed broad research of the literature pertaining to our investigation via the MEDLINE/PubMed database.

Results

It has been proven that FLC determination can provide rapid information about intrathecal inflammation in patients with multiple sclerosis. Moreover, literature data suggest that free light chain determination is the most interesting alternative for oligoclonal band analysis. In the present review, we also described that HIV-related immune system dysfunction is associated with an elevated concentration of serum-free light chains. Additionally, FLCs are potentially a strong and sensitive predictor of the risk of developing HIV-associated lymphomas.

Conclusion

Based on these published findings, we suggest that free light chains have high diagnostic sensitivity, which probably enables application in laboratory diagnostics.

Transitions of CDR-L3 Loop Canonical Cluster Conformations on the Micro-to-Millisecond Timescale

Sequence and structural diversity of antibodies are concentrated on six hypervariable loops, also known as the complementarity determining regions (CDRs). Five of six antibody CDR loops presumably adopt a so-called canonical structure out of a limited number of conformations. However, here we show for four antibody CDR-L3 loops differing in length and sequence, that each loop undergoes conformational transitions between different canonical structures. By extensive sampling in combination with Markov-state models we reconstruct the kinetics and probabilities of the transitions between canonical structures. Additionally, for these four CDR-L3 loops, we identify all relevant conformations in solution. Thereby we extend the model of static canonical structures to a dynamic conformational ensemble as a new paradigm in the field of antibody structure design.

Effect of VH-VL Families in Pertuzumab and Trastuzumab Recombinant Production, Her2 and FcγIIA Binding

Many therapeutic antibodies are humanized from animal sources. In the humanization process, complementarity determining region grafting is tedious and highly prone to failure. With seven known VH families, and up to six known κ VL families, there are choices aplenty. However, the functions of these families remain largely enigmatic. To study the role of these V-region families, we made 84 recombinant combinations of the various VH and VL family whole IgG1 variants of both Trastuzumab and Pertuzumab. We managed to purify 66 of these to investigate the biophysical characteristics: recombinant protein production, and both Her2 and FcγIIA binding. Our findings revealed combinations that showed improved recombinant antibody production and both antigen and receptor binding kinetics. These findings show the need to rethink antibodies as a whole protein, relooking of the functions of the antibody domains, and the need to include immunoglobulin receptor investigations for effective antibody therapeutics development.

Immunoglobulin gene expression in umbilical cord blood-derived CD34⁺ hematopoietic stem/progenitor cells

Recently, immunoglobulin (Ig) expression was reported in a variety of non-B lineage cells, including myeloid cells. We assessed whether hematopoietic stem/progenitor cells (HSC/HPCs) can express Ig. With Gene Expression Omnibus (GEO) microarray database analysis, we found that IGHM was expressed with the highest frequency and level in umbilical cord blood CD34(+) HSC/HPCs, followed by IGK@, IGHE, IGHD, IGHG1, and IGHA1, while IGL@ was nearly not expressed. Ig expression was further confirmed by molecular experiments and immunofluorescence. Moreover, HSC/HPCs-derived Ig displayed restricted/biased usages and VHDJH rearrangement patterns. These results suggest that Igs, especially IgM, may have a role in CD34(+) HSC/HPCs function.

In situ visualisation of immunoglobulin genes in normal and malignant lymphoid cells

Aims-To directly visualise immunoglobulin (Ig) heavy (H) and light chain genes (kappa and lambda) in metaphase chromosomes and interphase nuclei of normal and malignant lymphocytes using small genomic probes targeted to intragenic sequences.Methods-Cytogenetic preparations from phytohaemagglutinin stimulated lymphocytes, B-chronic lymphocytic leukaemia (B-CLL) cells, and a B-prolymphocytic leukaemia (B-PLL) cell line, containing a t(11;14), were hybridised in situ using biotin or digoxigenin labelled plasmid probes. The kappa genes were visualised with a combination of probes for the Ckappa, Jkappa, Vkappa1, and Vkappa2 segments, the lambda genes with a probe containing the Jlambda2-Clambda2, Jlambda3-Clambda3 segments and the H genes with a probe for Clambda2. Hybridisation sites were visualised using appropriate fluorochrome conjugates and images were analysed by digital microscopy.Results-In both normal and malignant lymphoid cells, the kappa and lambda genes were visualised as a single dot signal, whereas the H lambda genes were resolved as either two or three separate signals per chromatid in metaphase chromosomes or per allele in interphase nuclei. In the malignant PLL cells, double hybridisation experiments with a painting library specific for the chromosome 11 showed that the lambda region was retained in the translocated chromosome, with an in situ resolution pattern similar to that of the normal allele.Conclusions-This study shows that a high resolution in situ analysis of the three Ig loci can be efficiently performed with small size genomic probes on both normal and malignant lymphoid cells. Such an approach offers a flexible tool for the molecular characterisations of these loci on chromosomes and individual neoplastic cells.

Immunoglobulin expression in non-lymphoid lineage and neoplastic cells

It has traditionally been believed that the production of immunoglobulin (Ig) molecules is restricted to B lineage cells. However, immunoglobulin genes and proteins have been recently found in a variety of types of cancer cells, as well as some proliferating epithelial cells and neurons. The immunoglobulin molecules expressed by these cells consist predominantly of IgG, IgM, and IgA, and the light chains expressed are mainly kappa chains. Recombination activating genes 1 and 2, which are required for V(D)J recombination, are also expressed in these cells. Knowledge about the function of these non-lymphoid cell-derived immunoglobulins is limited. Preliminary data suggests that Ig secreted by epithelial cancer cells has some unidentified capacity to promote the growth and survival of tumor cells. As immunoglobulins are known to have a wide spectrum of important functions, the discovery of non-lymphoid cells and cancers that produce immunoglobulin calls for in-depth investigation of the functional and pathological significance of this previously unrecognized phenomenon.

Study of GM immunoglobulin allotypic system in Berbers and Arabs from Morocco

The GM immunoglobulin allotype polymorphism was investigated in four Moroccan populations: three Berber groups from Khenifra (Middle Atlas), Amizmiz (High Atlas), and Bouhria (Beni Snassen) and one Arabic-speaking sample from the Doukkala area (Abda, Chaouia, Doukkali, and Tadla districts in south-central Morocco). In order to characterize the genetic relationships between the populations, our results were compared with those obtained for other North African groups (from Morocco, Algeria, Tunisia, and Niger) and for Middle-East Africans, sub-Saharans, and Southwest Europeans. Based on GM haplotype frequencies, Factorial Correspondence Analyses, F(ST) significance testing, and hierarchical analyses of variance were performed. Our results reveal that Moroccan populations have heterogeneous GM profiles with high frequencies of GM haplotypes in Europeans (from 76% for Doukkala to 88% for Bouhria) and relatively high frequencies of GM haplotypes in sub-Saharans (from 11% for Bouhria to 23% for Amizmiz). The genetic diversity observed among Moroccans is not significantly correlated with either geographic or linguistic differentiation. In spite of their cultural and historical differentiation, we did not discover any significant genetic differences between Berbers and Arabic-speakers from Morocco. However, when large geographical areas are considered, our population samples are integrated in the North African GM variation, significantly distant from sub-Saharan groups but with a close relationship with Southwest European populations.

Genomic EcoRI polymorphism and cosmid sequencing reveal an insertion/deletion and a new IGLV5 allele in the human immunoglobulin lambda variable locus (22q11.2/IGLV)

The human immunoglobulin lambda locus ( IGL) is mapped at Chromosome 22q11.2, spanning about 1 Mb of DNA, and directs the synthesis of lambda-type immunoglobulin light chains. The positions of about 73-74 germline V-lambda genes, depending on the haplotypes, are known, with 29-33 of them being functional IGLV genes. These genes were divided into 11 subgroups ( IGLV1 to IGLV11) distributed into three gene clusters ( VA, VB, and VC). We constructed a high-resolution restriction map of a 37-kb cosmid clone (cosmid 8.3) harboring genes of the IGLV1, IGLV7, and IGLV5 families and the non-coding sequences IGLV(I)-42 and IGLV(VII)-41-1, located at cluster VB of the IGL locus. These IGLV genes were associated with unique EcoRI fragments detectable in Southern blots of genomic DNA. Population RFLP has revealed new IGLV alleles and haplotypes. We used the restriction map of cosmid 8.3 and the IMGT database as a reference for RFLP studies. EcoRI Southern blot hybridizations with subgroup-specific probes of the functional and open reading frame sequences present in cosmid 8.3 revealed different frequencies of IGLV gene fragments, as well as deletions of IGLV1-50 and IGLV5-39 genes and RFLP involving IGLV5-45 and IGLV5-48 genes. All members of the IGLV7 subgroup were monomorphic. Sequencing of the genes present in cosmid 8.3 revealed a new allelic variant of the IGLV5 subgroup. These data contribute to a better understanding of the contribution of the germline IGLV genes to the human genetic background and polymorphism.

Detection of immunoglobulin heavy chain gene rearrangements in hematologic malignancies

B-cell precursors undergo a unique somatic immunoglobulin heavy chain gene rearrangement process. The generated VHDHJH junction is a successful marker in lymphoproliferative malignancies at initial diagnosis for detection of clonality and during treatment for monitoring minimal residual disease. VHDHJH errors are often involved in recurring structural chromosomal aberrations of lymphoid malignancies, with consequent deregulated expression of the juxtaposed oncogenes, e.g., c-myc, bcl-2 or CCND1. Besides cytogenetics, a variety of molecular techniques are becoming increasingly established, including Southern blotting, PCR and real-time PCR, as well as fluorescence in situ hybridisation. Different approaches may be chosen to evaluate lymphoid malignancies either at diagnosis or follow-up in the light of increasing relevance and proven clinical utility.

Regulation of B lymphocyte differentiation

LEARNING OBJECTIVES

Type I hypersensitivity reactions uniquely involve the IgE class of immunoglobulins (Ig). IgE differs from other classes of Ig in that the majority of the antibodies are bound to high affinity IgE Fc(epsilon)Rs that are expressed on a variety of cell types. Some of these cell types, most notably, mast cells and basophils, are triggered to undergo rapid activation, degranulation, and release of bioactive mediators following binding of antigen to Fc(epsilon)RI-bound IgE. Because of the central role that IgE antibodies and these mediators play in the tissue injury typical of type I hypersensitivity, this article will review the various stages of B lymphocyte development, activation, and differentiation and comment, where appropriate on potential sites of deregulation in allergic disease.

DATA SOURCES

A literature search of the stages of B lymphocyte differentiation with emphasis on events that concern IgE expression was performed.

RESULTS

B lymphocyte differentiation into IgE expressing cells is dependent upon three types of signals. The first signal is delivered through the B cell antigen receptor and is pivotal in determining the antigenic specificity of the response. The second signal is provided primarily by cytokines derived from T helper 2 (TH2) cells, ie, interleukin (IL)-4 and IL-13. These cytokines are under tight regulation and their role appears to be the stimulation of transcription through the Ig constant region genes. Finally, the third signal is provided via the interaction between the constitutively expressed CD40 molecule on B lymphocytes and CD154 (CD40 ligand), a molecule expressed on T lymphocytes following activation. Elevated levels of IgE in atopic individuals may result from the preferential activation of TH2 cells.

CONCLUSIONS

A greater understanding of the regulation of IgE expression may be central to the development of more effective immunotherapy strategies designed to attenuate IgE synthesis.

Genetic markers of immunoglobulins and diabetes mellitus in the multiracial population of New Caledonia. The CALDIA Study Group

GM and KM immunoglobulin allotypes, which are the markers, respectively, of the constant parts of the heavy and the light chains of the IgG1, IgG2 and IgG3 subclasses, have been analysed in diabetic mellitus patients and controls living in New Caledonia. We tested 40 Europeans, 256 Melanesians and 44 Polynesians, as well as their 340 matched controls, in order to search for a genetic susceptibility at those polymorphic loci. All the subjects were tested for G1M (1, 2, 3, 17), G2M (23), G3M (5, 6, 10, 11, 13, 14, 15, 16, 21, 24, 28) and KM (1) by the classical hemagglutination method. The frequencies of GM haplotypes and KM alleles have been estimated by a maximum likelihood method. The results are in favour of no influence of the GM and KM loci. The prevalence of diabetes mellitus varies in the populations of New Caledonia: Polynesians are at much higher risk than Melanesians or Europeans. The GM haplotype distribution differs among ethnic groups; so they provide a useful marker to measure genetic admixture. The higher prevalence of diabetes observed among New Caledonians of European origin compared to the prevalence in Europe may be explained by genetic admixture with neighbouring Pacific populations, notably Polynesians (Asian haplotypes are present at a frequency of 9.4%). So, the genetic admixture should be measured in any genetic epidemiological study.

The complete nucleotide sequence of the human immunoglobulin heavy chain variable region locus

The complete nucleotide sequence of the 957-kb DNA of the human immunoglobulin heavy chain variable (VH) region locus was determined and 43 novel VH segments were identified. The region contains 123 VH segments classifiable into seven different families, of which 79 are pseudogenes. Of the 44 VH segments with an open reading frame, 39 are expressed as heavy chain proteins and 1 as mRNA, while the remaining 4 are not found in immunoglobulin cDNAs. Combinatorial diversity of VH region was calculated to be approximately 6,000. Conservation of the promoter and recombination signal sequences was observed to be higher in functional VH segments than in pseudogenes. Phylogenetic analysis of 114 VH segments clearly showed clustering of the VH segments of each family. However, an independent branch in the tree contained a single VH, V4-44.1P, sharing similar levels of homology to human VH families and to those of other vertebrates. Comparison between different copies of homologous units that appear repeatedly across the locus clearly demonstrates that dynamic DNA reorganization of the locus took place at least eight times between 133 and 10 million years ago. One nonimmunoglobulin gene of unknown function was identified in the intergenic region.

Physical map and one-megabase sequencing of the human immunoglobulin lambda locus

The human immunoglobulin lambda (IGL) locus is located on chromosome 22q11.1-q11.2 and contains the genes responsible for the immunoglobulin lambda light chains. This locus was recently mapped (physical map) and its 1-Mb DNA totally sequenced. In this review we focus on the characterization of the v-lambda genes, its chromosomal location, genomics and sequencing of the IGL locus.

FISH mapping of seven cDNA sequences in the pig

Fluorescence in situ hybridization (FISH) technique was applied to localize seven clones derived from a porcine (SSC) intestinal directionally cloned cDNA library. The size of the clones ranged from 1.1 to 1.3 kb. Three of the clones corresponded to histidyl-tRNA synthetase (HARS), immunoglobulin alpha (IGA) and lysozyme (LYZ) and mapped to SSC2q28-q29, 7q2.6 and 5p11 respectively. The available human-pig comparative painting data and sequence homology comparisons assisted in a tentative identification of the other three clones as glutathione-S-transferase (GST), glutathione-S-transferase mu (GSTM1) and immunoglobulin lambda gene cluster (IGL@). These clones mapped to SSC14q21, 5q2.4 and 14q22-q23 respectively. The remaining clone representing an EST mapped to 1p24-p25. These localizations contribute to the transcript map in pig and are significant as comparative markers. Difficulties associated with the mapping of small sequences using FISH are discussed.

A 37-kb restriction map of the human immunoglobulin lambda variable locus, VB cluster, harboring four functional genes and two non-coding Vl sequences

The human immunoglobulin lambda variable locus (IGLV) is mapped at chromosome 22 band q11.1-q11.2. The 30 functional germline v-lambda genes sequenced untill now have been subgrouped into 10 families (V<FONT FACE="Symbol">l</font>1 to V<FONT FACE="Symbol">l</font>10). The number of V<FONT FACE="Symbol">l</font> genes has been estimated at approximately 70. This locus is formed by three gene clusters (VA, VB and VC) that encompass the variable coding genes (V) responsible for the synthesis of lambda-type Ig light chains, and the J<FONT FACE="Symbol">l</font>-C<FONT FACE="Symbol">l</font> cluster with the joining segments and the constant genes. Recently the entire variable lambda gene locus was mapped by contig methodology and its one- megabase DNA totally sequenced. All the known functional V-lambda genes and pseudogenes were located. We screened a human genomic DNA cosmid library and isolated a clone with an insert of 37 kb (cosmid 8.3) encompassing four functional genes (IGLV7S1, IGLV1S1, IGLV1S2 and IGLV5a), a pseudogene (V<FONT FACE="Symbol">l</font>A) and a vestigial sequence (vg1) to study in detail the positions of the restriction sites surrounding the V<FONT FACE="Symbol">l</font> genes. We generated a high resolution restriction map, locating 31 restriction sites in 37 kb of the VB cluster, a region rich in functional V<FONT FACE="Symbol">l</font> genes. This mapping information opens the perspective for further RFLP studies and sequencing

EcoRI restriction fragment-length polymorphism of the human immunoglobulin variable lambda 8 (IGLV8) subgroup reveals a gene family

The human immunoglobulin lambda locus (IGL) maps on chromosome 22q11.1-q11.2 and directs the synthesis of lambda-type Ig light chains. This locus is formed by three gene clusters (VA, VB and VC) that encompass the variable coding genes and the J-C cluster plus the joining segments and the constant genes. Recently the variable lambda gene clusters were mapped by the contig methodology which located all the known functional v-lambda genes and pseudogenes. The 30 functional v-lambda genes described so far were subgrouped into ten families (V lambda I to V lambda X), but RFLP studies have estimated that the germline repertoire contains about 70 genes. Based on sequence comparisons, we defined specific oligonucleotide primers for the unique IGLV8S1 gene described. The cloned 244 bp product obtained from genomic DNA with these primers was sequenced and used as probe in Southern hybridization EcoRI RFLP analysis of Brazilian people. We detected the IGLV8S1 gene in a 3.7 kb EcoRI restriction fragment present in all the individuals analyzed, in agreement with the physical map of the IGL locus. Moreover, we detected an 8.0 kb EcoRI monomorphic fragment and a 6.0 kb EcoRI polymorphic fragment. These data suggest that the IGLV8 subgroup is a gene family.

Immunoglobulin lambda light chain orphons on human chromosome 8q11.2

We have identified two V lambda genes outside the major lambda locus on chromosome 22q11.2, and shown that they reside on chromosome 8q11.2. One gene (Orphée1), hybridizing strongly to the V lambda probes, was sequenced and found to belong to the V lambda 8 family; the other gene (Orphée2) only hybridized weakly. Orphée1 was present in all individuals tested (140) from three different populations, and was also found in gorillas. We envisage that these genes were generated by duplication and translocation of the V lambda 8a gene (and a V lambda pseudogene) from the major locus, and that this event occurred before the evolutionary divergence of humans and gorillas. As there is no other evidence for V lambda genes outside the major locus, it appears that the human lambda locus has undergone considerably less evolutionary shuffling than either the human light chain kappa locus or the heavy chain locus.

Human B cell biology

Human B lymphocytes share one major distinctive feature with B cells of other higher animals, namely the ability to generate and secrete immunoglobulins. These highly specialized proteins are capable of tremendous diversity, and thereby account for much of our immune protection against invading organisms. Despite the great potential diversity possible in the specificities of immunoglobulin molecules, however, the binding of antibody to antigen initiates a limited spectrum of biologically important effector functions, such as complement activation and/or adherence of the immune complex to receptors on leukocytes. A variety of mechanisms have been elucidated that account for this, not all of which are shared by the different types of animals capable of making these proteins. The purpose of this chapter is to review the genetic, developmental, and physiologic mechanisms critical for human B cell expression of immunoglobulin.

Isolation and characterization of mouse dishevelled-3

The Drosophila dishevelled (dsh) segment polarity gene is required to establish cell fates specified by wingless/Wnt signal transduction during development. We have previously reported the cloning and characterization of a mouse homolog of dishevelled, Dvl1. Utilizing RT-PCR with degenerate primers, we isolated another member of the mouse Dishevelled (Dvl) gene family, Dvl3. The Dvl3 gene maps to mouse chromosome 16. The predicted amino acid sequence shares 64 and 62% identity to Dvl1 and Dvl2, respectively. The region of highest conservation between all three Dvl coding regions, at 97% identity, is noted at the PDZ domain (also termed the DHR domain or GLGF motif), a motif of 60 amino acids present in all dishevelled encoded proteins and first described in the Drosophila discs large (dlg) tumor suppressor gene. In adult mice, Dvl3 expression is widespread with highest levels exhibited in brain, ovary, and heart. In embryos, Dvl3 is expressed in every tissue between 7.5 and 9.5 days postcoitum, and by 10.5 days postcoitum highest expression was seen in the dorsal root ganglia, somites, limb buds, branchial arches, heart, gut and throughout the developing central nervous system.

Generation of a high-resolution genetic map and a YAC contig of the Lurcher locus on mouse chromosome 6

Lurcher (Lc) is a semidominant mouse mutant that displays progressive neurodegeneration during perinatal development. This genetic lesion results in apoptotic neuronal death in a dosage dependent and cell autonomous manner in specific neurons during their terminal differentiation. To understand the molecular basis of the Lc mutation, we have adopted a positional cloning approach based on its location on mouse chromosome 6. To define the Lc locus, we have extended our previous analysis of an intersubspecific backcross between Mus m. castaneus and B6CBACa-Aw-j/A-Lc consisting of 504 animals (Norman et al. 1991). In addition, 580 animals of a generic backcross between Mus spretus and C57BL/6 (The European Collaborative Interspecific Backcross) were utilized for the fine genetic mapping of the Lc locus. Using three RFLP markers and nine microsatellite markers in the vicinity of the Lc locus, we determined the order and relative genetic distances of these markers at a resolution of 0.1 cM. The Lc mutation was mapped between two flanking markers, D6Mit121 and D6Mit175, separated by a genetic distance of 0.5 cM. We then initiated the cloning of the genomic region surrounding these two markers by screening a YAC library and characterizing YAC end sequences for further screening. This effort has resulted in the construction of a YAC contig consisting of 14 YACs and spanning a 3-Mb region. Markers isolated from these YACs were used to further define the Lc locus, resulting in a physical map that places the Lc gene within an estimated 300-kb interval. This set of YACs and markers will serve as DNA sources for the identification of the Lc gene.

Long-term production of human monoclonal antibodies by human-mouse heterohybridomas

Production of monoclonal antibodies (mAbs) by fused somatic cells was first developed by Köhler and Milstein two decades ago, but its utilization for the production of human mAbs, particularly those bearing kappa chains, has been difficult because heterohybridomas formed with mouse myeloma cells are unstable and tend to lose certain of their human chromosomes. We have stabilized two such heterohybridomas over one year period and induced the production of kappa-bearing and lambda-bearing human mAb, respectively. Increased productivity was achieved by adding the Na+K(+)-ATPase inhibitor, ouabain and a cell mitosis inhibitor, cytochalasin B, to the cell culture media.

Origin of high-grade lymphomas in Richter syndrome

Patients with B cell chronic lymphocytic leukemia (CLL) occasionally develop high-grade B cell lymphomas that are associated with constitutional symptoms, rapidly progressive lymphadenopathy, and swift clinical deterioration. Now known as Richter syndrome, this symptom complex develops in approximately 5% of all patients with CLL. Structural and molecular analysis of the immunoglobulin (Ig) genes have allowed investigators to define the clonal relationship between the leukemia and lymphoma cells of a given patient. In most cases the aggressive lymphoma evolves from the original leukemia cell clone. However, in some cases the lymphoma apparently represents a second malignancy. Differentiation between these two types of lymphoma may have clinical significance. Further investigation is required to allow for identification of CLL patients who are at risk for developing Richter syndrome and to understand factors involved in its etiopathogenesis.

Comparative mapping of DNA probes derived from the V kappa immunoglobulin gene regions on human and great ape chromosomes by fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH) of cosmid clones of human V kappa gene regions to human and primate chromosomes contributed to the dating of chromosome reorganizations in evolution. A clone from the kappa locus at 2p11-p12 (cos 106) hybridized to the assumed homologous chromosome bands in the chimpanzees Pan troglodytes (PTR) and P. paniscus (PPA), the Gorilla gorilla (GGO), and the orangutan Pongo pygmaeus (PPY). Human and both chimpanzees differed from gorilla and orangutan by the mapping of cos 170, a clone derived from chromosome 2cen-q11.2; the transposition of this orphon to the other side of the centromere can, therefore, be dated after the human/chimpanzee and gorilla divergence. Hybridization to homologous bands was also found with a cosmid clone containing a V kappa I orphon located on chromosome 1 (cos 115, main signal at 1q31-q32), although the probe is not fully unique. Also, a clone derived from the orphon V kappa region on chromosome 22q11 (cos 121) hybridized to the homologous bands in the great apes. This indicates that the orphons on human chromosomes 1 and 22 had been translocated early in primate evolution.

Chromosomal localization of the gamma-glutamyl carboxylase gene at 2p12

We have used two complementary approaches to analyze the chromosomal location of the gamma-glutamyl carboxylase gene. The amplification of a carboxylase-specific genomic fragment by polymerase chain reaction (PCR) in a human-rodent hybrid cell mapping panel localized the gene to chromosome 2. Mapping by fluorescence in situ hybridization assigned the gene to p12 of chromosome 2. Our results indicate that the gamma-glutamyl carboxylase gene has a single locus in the human genome.

Isolation of the human peroxisome proliferator activated receptor gamma cDNA: expression in hematopoietic cells and chromosomal mapping

The nuclear receptor superfamily of transcription factors, which includes the retinoic acid receptors and v-erb A, play important roles in the molecular control of hematopoiesis. To identify nuclear receptors expressed in hematopoietic cells, we screened a human bone marrow cDNA library using a degenerate oligonucleotide and isolated a 1.85-kb full-length cDNA encoding a new human member of this superfamily, the peroxisome proliferator activated receptor gamma (hPPAR gamma). Two different hPPAR gamma transcripts were expressed in hematopoietic cells: a 1.85-kb transcript, which corresponds to the full-length mRNA (PPAR gamma 1), and a 0.65-kb transcript (PPAR gamma 2), which cannot encode all of the nuclear receptor functional domains. Normal neutrophils and peripheral blood lymphocytes, as well as circulating leukemic cells from patients with AML, ALL, and CML, express only PPAR gamma 2 on Northern blot analysis. In contrast, only the PPAR gamma 1 transcript was detected in a variety of human leukemia cell lines and in cultured normal primary bone marrow stromal cells. Both transcripts were detected in various fetal and adult nonhematopoietic tissues. We mapped the location of the hPPAR gamma gene to human chromosome 3p25 by somatic cell hybridization and linkage analysis. PPARs have been shown to be activated by peroxisome proliferating agents, long-chain fatty acids and arachidonic acid. Human PPAR gamma, although homologous to the PPAR gamma s of other species, has unique sequence and amino acid differences. Identification of hPPAR gamma will allow further understanding of its role in human cellular leukotriene, prostaglandin, and peroxide degradative or synthetic pathways, as well as its role in lipid metabolism and regulation of adipocyte differentiation.

Genetic mapping in human and mouse of the locus encoding TRBP, a protein that binds the TAR region of the human immunodeficiency virus (HIV-1)

Productive infection with HIV-1, the virus responsible for AIDS, requires the involvement of host cell factors for completion of the replicative cycle, but the identification of these factors and elucidation of their specific functions has been difficult. A human cDNA, TRBP, was recently cloned and characterized as a positive regulator of gene expression that binds to the TAR region of the HIV-1 genome. Here we demonstrate that this factor is encoded by a gene, TARBP2, that maps to human chromosome 12 and mouse chromosome 15, and we also identify and map one human pseudogene (TARBP2P) and two mouse TRBP-related sequences (Tarbp2-rs1, Tarbp2-rs2). The map location of the expressed gene identifies it as a candidate for the previously identified factor encoded on human chromosome 12 that has been shown to be important for expression of HIV-1 genes. Western blotting indicates that despite high sequence conservation in human and mouse, the TARBP2 protein differs in apparent size in primate and rodent cells.

Immunoglobulin allotypes (GM and KM) and their interactions with HLA antigens in autoimmune diseases: a review

GM and KM immunoglobulin (Ig) allotypes and their interactions with HLA antigens have been analyzed in various autoimmune diseases: multiple sclerosis, rheumatoid arthritis, insulin-dependent diabetes mellitus (IDDM), systemic lupus erythematosus, coeliac disease, Crohn's disease, Graves' disease, atrophic thyroiditis, Hashimoto's thyroiditis, myasthenia gravis, chronic active hepatitis, alopecia areata, uveitis, vitiligo, Turner's syndrome, glomerular nephritis, Berger's disease and idiopathic dilated cardiomyopathy. This review reports published results about associations or linkages, as well as the origins of the populations, the numbers of patients and controls tested. The possible role of Ig polymorphisms in the physiopathology of autoimmune diseases is discussed. Ig allotypes and statistical methods used to analyse the HLA and Ig data are also described.

A processed J chain pseudogene on human chromosome 8 that is shared by several primate species

Human DNA contains two sequences that hybridize to a human J chain gene probe: the J chain gene itself and a second previously uncharacterized sequence. By cloning and sequence analysis we now show this related sequence to be a processed pseudogene, which we have localized using somatic hybrids to chromosome 8 (distinct from the functional gene on chromosome 4) and mapped by linkage analysis to 8q13-q21. The pseudogene provides evidence of an additional DNA insertion event as it contains an AluI element embedded in sequence corresponding to the 3' untranslated region of the gene. The extent of sequence divergence between the pseudogene and the functional J chain gene suggests that the pseudogene was created roughly 40-50 million years ago; consistent with this estimate, Southern blots suggest that the pseudogene is shared by great apes as well as Old World monkeys.

Gm and Km allotypes in Wayampi, Wayana and Emerillon Indians from French Guiana

We have studied 506 Amerindians from three French Guiana groups: 194 Wayampi, living in Trois-Sauts, and 100 in the Camopi area; 47 Emerillon also living in the Camopi area and 165 Wayana on the Litani and Maroni rivers. All samples were tested for G1m(1,2,3,17), G3m(5,6,10,11,13,14,15,16,21,24,28) and Km(1) by the classical method of hemaglutination inhibition. The phenotype and haplotype distributions are presented and have been subjected to factorial correspondence analysis. Two Gm haplotypes are common: Gm1,17;21,28, and Gm1,2,17;21,28, but with an important variation in frequency. A rare haplotype, probably the result of a genetic anomaly: Gm1,17;21R,28, is frequent in the Emerillon (17%). These populations show no evidence of Black or Caucasian admixtures.

A directory of human germ-line V kappa segments reveals a strong bias in their usage

From the genomic DNA of a single individual, we have amplified, cloned and sequenced 37 human germ-line V kappa segments. Four of these segments were new. We then compiled a comprehensive directory of all germ-line V kappa segments and identified 50 different sequences with open reading frames. Comparison with 236 rearranged sequences revealed that no more than 24 of these germ-line sequences could be assigned rearranged counterparts, that some of these were rarely used, and that only about 11 sequences are used frequently. This suggests that the expressed V kappa repertoire is mainly derived from a limited number of segments. Most surprisingly, the J kappa-distal region of the locus appears to be rarely used: we could unambiguously assign 162 rearranged sequences to V kappa segments of the J kappa-proximal region, but only 5 to segments of the J kappa-distal region.

Glycosylation-dependent activity of baculovirus-expressed human liver carboxylesterases: cDNA cloning and characterization of two highly similar enzyme forms

A cDNA, designated hCE, encoding the entire sequence of a carboxylesterase, was isolated from a human liver lambda gt11 library. The hCE-deduced protein sequence contained 568 amino acids, including an 18 amino acid signal peptide sequence, and had a calculated molecular mass of the mature protein of 60,609 Da. A second cDNA, designated hCEv, was isolated from the same lambda gt11 library and contained a 3-bp deletion resulting in the loss of the final amino acid in the signal peptide sequence (Ala-1) and a second 3-bp deletion leading to an in-frame loss of Gln345. Expression of mRNA corresponding to both hCE and hCEv was detected in eight adult human liver samples, with individual levels varying 5-fold (hCE) and 12-fold (hCEv). A single immunoreactive protein was detected in 13 adult human liver samples when probed with antibody directed against a rat carboxylesterase. Based on allele-specific oligonucleotide hybridizations, we believe that the hCE and hCEv cDNAs represent two distinct members of the carboxylesterase family. The carboxylesterase genes were localized to human chromosome 16 using a somatic cell hybrid mapping strategy. Baculovirus expression of hCE in Sf9 cells produced a protein with an estimated molecular mass of 59,000 Da. This enzyme was able to hydrolyze aromatic and aliphatic esters but possessed no catalytic activity toward amides or a fatty acyl CoA ester. Baculovirus-mediated expression of the hCEv cDNA yielded a second protein of 56,000 Da resulting from inefficient N-glycosylation of the hCEv protein. Although the substrate specificity for the hCEv protein was identical to that of expressed hCE for any given substrate, the specific activity for the hCE protein was always higher than that for the hCEv protein. Tunicamycin inhibition studies provided the first evidence that N-glycosylation of these luminal enzymes is essential for maximal catalytic activity.

The little (lit) mutation cosegregates with the growth hormone releasing factor receptor on mouse chromosome 6

The little (lit) autosomal recessive mutation in the mouse causes dwarfism due to isolated growth hormone deficiency. The in vitro physiology of pituitary growth hormone release in lit/lit animals suggests that an abnormality in the growth hormone releasing factor (GRF) receptor (Ghrfr) is a very likely candidate for the lit mutation. We mapped Ghrfr to the region around lit on Chromosome (Chr) 6 in 100 chromosomes of an FVB x Czech II interspecific backcross. Molecular markers were Neuropeptide Y (Npy), homeobox (Hoxa2), immunoglobulin kappa chain (Igk), wingless-related MMTV integration site (Wnt-2), cystic fibrosis (Cftr), carboxypeptidase A (Cpa), and Ghrfr. Map order and distances were as follows: Cen-II-Wnt-2-(0 cM)-Cftr-(6.0 cM)-Cpa-(8.0 cM)-Npy-(1.0 cM)-Hoxa2-(3.0 cM)-Ghrfr-(2.0 cM)-Igk. We mapped lit (by phenotype) relative to Hoxa2 and Igk on 72 F2 chromosomes of offspring of a B6CZ lit/ + x B6FVB lit/ + intercross and 18 chromosomes of offspring of a B6FVB lit/ + intercross. Map order and distances were as follows: Hoxa2-(2.1 cM)-lit/Ghrfr-(3.7 cM)-Igk. No recombinations between lit and Ghrfr were detected. Thus, Ghrfr maps to mouse Chr 6 and may be allelic with lit. Amplification of a short segment at the 3' end of the Ghrfr mRNA by reverse transcription coupled to the polymerase chain reaction showed a greatly diminished level of GRF receptor mRNA in the pituitaries of lit/lit mice as compared with lit/ + controls. Low level of message could reflect a primary molecular defect or be due to secondary hypoplasia of somatotropes.(ABSTRACT TRUNCATED AT 250 WORDS)

Physical location of the human immunoglobulin lambda-like genes, 14.1, 16.1, and 16.2

The human immunoglobulin lambda-like (IGLL) genes, which are homologous to the human immunoglobulin lambda (IGL) light chain genes, are expressed only in pre-B cells and are involved in B cell development. Three IGLL genes, 14.1, 16.1, and 16.2 are present in humans as opposed to one, lambda 5 (Igll), found in the mouse. To precisely map the location of the human IGLL genes in relation to each other and to the human IGL gene locus, at 22q11.1-2, a somatic cell hybrid panel and pulsed field gel electrophoresis (PFGE) were used. Hybridization with a lambda-like gene-specific DNA probe to somatic cell hybrids revealed that these genes reside on 22q11.2 between the breakpoint cluster region (BCR) and the Ewing sarcoma breakpoint at 22q12 and that gene 16.1 was located distal to genes 14.1 and 16.2. Gene 14.1 was found by PFGE to be proximal to 16.2 by at least 30 kilobases (kb). A 210 kb Not I fragment containing genes 14.1 and 16.2 is adjacent to a 400 kb Not I fragment containing the BCR locus, which is just distal to the IGL-C (IGL constant region) genes. We have determined that the IGLL genes 14.1 and 16.2 are approximately 670 kb and 690 to 830 kb distal, respectively, to the 3'-most IGL-C gene in the IGL gene locus, IGL-C7. We thus show the first physical linkage of the IGL and the IGLL genes, 14.1 and 16.2. We discuss the relevance of methylation patterns and CpG islands to expression, and the evolutionary significance of the IGLL gene duplications. Consistent with the GenBank nomenclature, these human IGLL genes will be referred to as IGLL1 (14.1), IGLL2 (16.2), and IGLL3 (16.1), reflecting their position on chromosome 22, as established by this report.

The genes for CD37, CD53, and R2, all members of a novel gene family, are located on different chromosomes

CD37, CD53, and R2 leukocyte surface antigens are members of a novel family of structurally related proteins. They all have four transmembrane-spanning domains with a single major extracellular loop. The CD37 is expressed on B cells and on a subpopulation of T cells. The CD53 is known as a panleukocyte marker. The R2 protein is an activation antigen of T cells. The CD37, CD53, and R2 genes were assigned with the help of human/rodent somatic cell hybrids and human-specific probes to human chromosomes 19, 1, and 11, respectively. For the regional assignment, various deletion hybrids were used to map CD37 to 19p13-q13.4, CD53 to 1p12-p31, and R2 to 11p12.